Contact attachment for current indicators



March 17, 1942. w. oLsoN CONTACT ATTACHMENT FOR CURRENT INDICATORS FiledMarch 51, 1941 Patented Mar. 17, 1942 FFEQE CONTACT ATTACHMENT FORCURRENT INDICATORS Walter Olson, Glasco, Kans.

Application March 31, 1941, Serial No. 386,164

5 Claims.

This, invention is an attachment for currentindicating devices such asvoltmeters, ammeters and the like, although not limited to thesespecific types of indicators.

One of the objects of the invention is to provide a simple andinexpensive device by means of which contact may conveniently be madewith the circuit to be tested, and the reading of the instrument begreatly facilitated. A further object is to provide a device of thecharacter mentioned which is provided with a rigid contact normally incircuit with the indicating instrument, and a second adjustably mountedcontact which may selectively be connected with said circuit. A furtherobject is to provide an adjustably mounted contact having means by whichit may be detachably connected with an element in the circuit to betested.

The invention will be hereinafter fully set forth and particularlypointed out in the claims.

In the accompanying drawing- Figure 1 is a view illustrating anelectrical indicating device connected with an attachment constructed inaccordance with the invention. Figure 2 is an enlarged longitudinalsectional view of said attachment with the adjustably mounted contact ininoperative position. Figure 3 is a similar view with said contact incircuitclosed position. Figure 4 is a detail view illustrating saidadjustable contact. Figure 5 is a similar view illustrating a slightmodification.

Referring to the drawing, l designates a tubular barrel constructed ofany suitable dielectric material, such as any one of the well knownsynthetic resins. Said barrel is provided at one end with an internallythreaded portion indicated at H.

Removably mounted within the threaded end of the barrel I0 is a plug P,having an externally threaded stem l2 complemental to the threadedportion H, and also having an enlarged contact portion l3 ofapproximately the same external diameter as that of the barrel H). Theenlargement is also provides a shoulder which acts as an abutmentengageable with the adjacent end of the barrel I0, so as to limit inwardtravel of the plug. The plug also has a shorter extension M which isexternally threaded to receive a nut I having a closing wall It adaptedto extend over the adjacent open end of the plug, and having an openingthrough which extends a contact pin l1. Said pin has a shoulder I8 whichis engaged by said nut, so as to rigidly retain it in position. The nutalso serves to retain in position a dielectric washer l9 and is normallyheld against rotation by being brazed or otherwise secured to theextension M. The pin H and plug P are connected to a suitable wire 20,which leads to a testing device A, such as an ammeter, or other wellknown current-indicating device, which is provided with a permanentcontact terminal 2!.

Slidingly mounted upon the exterior of the barrel I0 is a metal contactsleeve 25, which is provided with a radial arm 26 to which is secured aclip 2'], such as an ordinary spring actuated alligator clip.

In operation, the slide 26 is usually raised to a position in which thecontact sleeve 25 is out of engagement with the enlargement 13 of theplug P- In this position, the testing device may be operated by placingthe pin ll in contact with an element on one side of the circuit to betested, the exposed end of wire 2! being contacted with an element onthe other side of the circuit. A circuit will then be closed through theinstrument A, and a reading may then be taken in a well known manner.However, there are conditions where it might be more convenient ifengagement of one of the contacts with the circuit could be maintainedwithout the necessity of the operator holding it in operative position.In such event, the sleeve 25 is-slid downwardly, so as to cover theenlargement 13 of the plug P and thereby establish an electrical contacttherewith. This will bring the clip 21 well below the plane of the pin26, so that said clip may be secured to an element which is connectedwith one side of the circuit to be tested. For instance, in the case oftesting batteries, the clip may be engaged with one of the poles ofthebattery, leaving the operator free to hold the testing device A in onehand and the wire 2! in the other hand. Thus, the circuit to the testingdevice A will be closed from the clip 21 and sleeve 25 to theenlargement of plug I3 and wire 19. It is obvious, however, that thereare conditions of testing under which the device would be operativewithout regard to the relative positions of the pin H and the clip 2i.For instance, if the test is to be made from the loose end of a wire,the clip 21 may be caused to grip an uncovered portion of the wirewithout any interierence as to its functions by the said pin H.

In Figure 5 is illustrated a fork-type of contact clip 2! which may besubstituted for the clip 21, if so desired. Said clip 21 is providedwith a contact sleeve 25 slidingly engaged with the barrel l0 andmovable into and out of engagement with plug P.

Having thus explained the nature of the invention and described anoperative manner of constructing and using the same, although withoutattempting to set forth all of the forms in which it may be made, or allof the forms of its use, what is claimed is:

1. In a current indicating device, a contact attachment comprising atubular barrel of dielectric material, a contact member mounted in oneend of the barrel and adapted to be connected with one side of anindicator circuit, said contact member having an enlarged contactportion, a contact sleeve sliding mounted on said dielectric barrel andengageable with said enlarged contact portion, and a second contactmember integrally connected to and carried by said slidable contactsleeve.

2. In a current indicating device, a contact attachment comprising atubular barrel of dielectric material, a plug having a reduced portioninserted into one end of the barrel and adapted to be connected with anelectric conductor, said plug having a pointed contact terminal and anenlarged intermediate contact portion abutting against the adjacent endof the barrel, a second contact member slidingly mounted on saiddielectric barrel and engageable with said enlarged contact portion, anda contact clip secured to and movable with said slidable contact member.

3. In a current indicating device, a contact attachment comprising atubular barrel of dielectric material, a plug removably mounted in oneend of said barrel and having a portion adapted for connection with anelectric conductor, said plug having a pointed contact terminal, andalso having an enlarged intermediate contact portion abutting againstthe adjacent end of the barrel and of approximately the same diameter'asthat of the barrel, a contact sleeve slidingly mounted on said barreland engageable with said enlarged contact portion, and a second contactterminal connected to and movable with said sleeve.

4. In a current indicating device, a contact attachment comprising atubular barrel of dielectric material, a hollow plug having a stemremovably mounted in one end of said barrel and adapted to be connectedwith an electric conductor, said plug having a pointed contact fixedlysecured thereto and also having an enlarged contact portion abuttingagainst the adjacent end of said barrel, a member slidingly mounted onsaid barrel and having a contact portion complemental to and engageablewith said enlarged contact portion, said sleeve having a radiallydisposed arm, and another contact member carried by said slidablemember.

5. In a current indicating device, a contact attachment comprising atubular barrel of dielectric material, a hollow plug having a stemremovably mounted in one end of said barrel and adapted to be connectedwith an electric conductor, said plug having a pointed contact fixedlysecured thereto and an enlarged intermediate contact portion abuttingagainst the adjacent end of said-barrel, said plug also having anaxially disposed threaded boss, a contact sleeve slidingly mounted onsaid barrel and engageable with said enlarged contact portion, saidsleeve having a radially disposed arm, a contact member carried by saidradially disposed arm, a dielectric washer through which said boss isextended, and a nut engageable with said boss and said Washer to retainthe latter in place and raving an opening through Which said fixedcontact protrudes.

WALTER OLSON.

